Species and cultivars, of cabbages and kings

Cereoid* cereoid at prodigy.net
Mon Oct 15 20:27:37 EST 2001


Dear David,

The answers to your questions are not very easy to answer. There are many
exceptions and certain criteria must exist for many hybrids to be fertile.

1. Is it true that all cultivars of the same species will be fertile with
each other?

Not necessarily, some cultivars may be sterile triploids or odd number
polyploids.

2. Can different species cross-pollinate and produce fully functional and
fertile offspring?

All depends. Some closely allied species are interfertile while other are
not. Species that are polyploid  more likely to be interfertile and produce
fertile offspring than are allied diploid species. Crosses between diploid
and polyploid species usually produce sterile hybrids with odd number ploidy
if they are successful at all.

Species with different basic chromosome numbers are typically not
interfertile. If they do produce hybrids, they are typically sterile unless
there is a spontaneous doubling of the chromosomes producing an
allopolyploid plant. The process is called instant speciation.

*********************

All the plants you mention are derived from species of Brassica or their
hybrids. Some are species of hybrid origin and the result of the doubling of
chromosomes. They are allopolyploids and not interfertile with the parent
species or other allied allopolyploid species. Their origin is complex and
much literature has been written on them. European cabbage, broccoli,
cauliflower and brussels sprouts are all derived from Brassica oleracea
(x=9). The Asiatic cabbages are derived from Brassica chinensis (B.rapa ssp.
chinensis) (x=10).

http://www.ultranet.com/~jkimball/BiologyPages/P/Polyploidy.html

http://www.actahort.org/books/467/467_37.htm


David Hare-Scott <syncreticsolutions at optushome.com.au> wrote in message
news:3uKy7.5126$bE1.23635 at news1.rdc1.nsw.optushome.com.au...
> Talking about sexually reproducing plants here.
> Is it true that all cultivars of the same species will be fertile with
each
> other?
> Can different species cross-pollinate and produce fully functional and
> fertile offspring?
>
> Talking about cabbages.
> In my supermarket there are cabbages (4 kinds), broccoli , cauliflower,
> brussels sprouts and Asian vegetables (about 8 kinds, buk choy, choy sum,
> wong buk etc)  that all look like members of the cabbage "family" to me.
> Are these all cultivars of one species, all different species, or several
> species and cultivars of those species?
>
> David
>
>





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